Update README.md

instructions for running compiler

Author: misino

README.md

@@ -19,3 +19,23 @@ Default: date = new Date()
 ```
 <DatepickerInput date={new Date()} />
 ```
+
+minified javascript and css are located in directory `src/build`
+
+###Development
+If you want to make changes in code and use benefits of compiling code, you need to have gulp and bower installed.
+
+```
+npm install -g gulp
+npm install -g bower
+```
+
+before running gulp for the first time, install dependencies and download other stuff via bower
+
+```
+cd react-datepicker
+npm install
+bower install
+```
+
+Compile code via command `gulp build` or `gulp`